dB Hearing Level Research Articles

Optimizing cochlear implant speech performance.

Results of studies performed in our laboratory suggest that cochlear implant recipients understand speech best if the following speech processor parameters are individually chosen for each person: minimum and maximum stimulation levels on each electrode in the speech processor program (MAP), stimulation rate, and speech coding strategy. If these and related parameters are chosen to make soft sounds (from approximately 100 to 6,000 Hz) audible at as close to 20 dB hearing level as possible and loud sounds not too loud, recipients have the opportunity to hear speech in everyday life situations that are of key importance to children who are learning language and to all recipients in terms of ease of communication.

Auditory steady-state response testing in children: evaluation of a new technology

The purpose of this study was to evaluate auditory steady-state responses (ASSR) for determining frequency-specific hearing impairment and to compare this technology with conventional auditory brainstem responses (ABR). Study design The study was a prospective clinical trial. Twenty-eight pediatric patients ranging in age from 7 to 61 months who were undergoing sedated ABR testing for evaluation of hearing impairment were also evaluated using ASSR. Estimated audiograms of the ASSR are compared with the ABR results. ASSR estimated audiograms with frequency-specific information were produced for all patients in whom an ABR recording was obtained. In 20 ears in which an ABR tracing was absent at the maximum level of 90 dB, 13 ears had measurable ASSR thresholds with an average threshold of 98.9 dB at 250 to 8000 Hz. ASSR showed sensitivity equal to that of ABR for individuals with hearing levels (HL) from 0 to 90 dB HL. In patients with hearing impairment greater than 90 dB normal HL (nHL), ASSR showed distinct advantage over ABR testing in that recordings were reliably produced up to 127 dB nHL.

Effect of Ipsilateral and Contralateral Low-frequency Narrow-band Noise on Temporary Threshold Shift in Humans

Objective – To evaluate the effect of ipsilateral and contralateral low-frequency (250 Hz) narrow-band noise (NBN) on the temporary threshold shift (TTS) induced by a 2 kHz tone in young normally hearing subjects with a functioning auditory efferent system.Material and Methods – Sixteen young volunteers served as subjects. All the subjects were young (20–30 years), disease-free and had a medical history negative for otological disease, noise exposure and use of ototoxic drugs. They had normal hearing [thresholds of 125–8000 Hz below 20 dB hearing level (HL)], transient-evoked otoacoustic emissions and contralateral suppression. The subjects were randomly assigned to one of three different groups. Subjects in Group A (n=5) were exposed to a 90 dB HL 2 kHz pure tone for 10 min. Subjects in Group B (n=6) were exposed to a 90 dB HL 2 kHz pure tone and an ipsilateral 45 dB HL 250 Hz NBN for 10 min. Subjects in Group C (n=5) were exposed to a 90 dB HL 2 kHz pure tone and a contralateral 45 dB HL 250 Hz NBN for 10 min. The right ear served as the test ear. The TTS 2 min after the end of the exposure (TTS2) was measured in all subjects at 2, 3 and 4 kHz.Results – TTS2 in Group A was significantly higher at 3 kHz (p=0.011) and at 4 kHz (p=0.003) than TTS2 in Group B. At 4 kHz, TTS2 in Group C was significantly higher (p=0.013) than TTS2 in Group B. Although TTS2 in Group C was lower than TTS2 in Group A, this difference was not significant. The presence of an ipsilateral low-frequency NBN significantly reduced TTS2 induced by a 90 dB HL 2 kHz tone. A contralateral low-frequency NBN reduced TTS2 in this group of subjects; however, the reduction was not significant.Conclusion – The results of this study show that an ipsilateral low-intensity, low-frequency (250 Hz) NBN can give protection from a TTS induced by a 2 kHz tone. Contralateral low-frequency NBN did not induce any protective effect.

Pure tone hearing thresholds and speech recognition scores in Dutch patients carrying mutations in the USH2A gene.

To establish the audiometric profile and speech recognition characteristics in 36 Usher IIa patients, carrying one (A) or two (B) pathogenic mutations in the gene. Family study. Tertiary referral center. Thirty six Usher IIa patients from 21 Dutch families. Ophthalmologic, vestibular, and audiometric examinations were performed on all patients. Cross-sectional analysis was performed on pure tone threshold data at 0.25 to 8 kHz and on speech phoneme recognition scores. Progression was evaluated using linear regression analysis on raw and presbyacusis corrected data. A downsloping audiogram was found, with a mean threshold slope of -9 dB per octave, that was mildly progressive, i.e., by approximately 0.5 dB per year. Individual monaural maximum phoneme recognition scores (% correct) were analyzed in 30 patients in relation to the patient's age and level of hearing impairment characterized by a pure tone average (PTA(1-4 kHz)). The speech recognition score started to deteriorate from a score of 90% at 38 years at a rate of 0.4% per year. The 90% level was attained at 69 dB hearing level (PTA(1-4 kHz)); at higher levels of impairment, the score deteriorated at a slope of 0.6% per dB hearing level. There was no significant difference between group A and B in pure tone threshold, with or without presbyacusis correction, or phoneme recognition score as related to age or PTA(1-4 kHz). Patients with various mutations in have moderate to severe hearing impairment showing mild progression at approximately 0.5 dB hearing level per year.

Hearing Deterioration in Patients with a Non-growing Vestibular Schwannoma

Objective--The aim of this study was to document and analyse the course of several audiometric parameters in 49 patients with a non-growing unilateral vestibular schwannoma (VS). Material and methods--Patients received conservative management and absence of tumour growth was ascertained by means of serial magnetic imaging studies. Pure-tone audiometry and speech audiometry were performed at yearly intervals. Results--Pure-tone audiometry revealed a significant increase in thresholds at all frequencies, except for 8.0 kHz. The maximum yearly threshold increase was 2.4 dB hearing level at 1.0 and 2.0 kHz. Speech audiometry revealed a significant decrease in maximum discrimination over the course of time. No significant changes were observed in the following parameters: the intensity level at which maximum discrimination was achieved; the roll-over index; the speech reception threshold; and the slope of the curve in the speech audiogram. No change was observed in the relation between pure-tone audiometry thresholds and speech audiometry scores. Apparently, the deterioration of pure-tone perception and speech discrimination ran parallel courses. Conclusions--The results of this study indicate that hearing loss is a predominant symptom in patients with a non-growing VS, as is also known in patients with a growing lesion. Moreover, it seems unlikely that the hearing loss in VS patients is merely the result of mechanical influences on retrocochlear neural or vascular structures.

Further delineation of the DFNA5 phenotype: results of speech recognition tests.

Speech recognition scores were analyzed in 34 carriers of a DFNA5 mutation. Cross-sectional linear regression analysis (last visit, maximum recognition score in %Correct on age or PTA1,2,4 kHz) established onset age (score 90%) at 16 years and onset PTA1,2,4 kHz level (score 90%) at 41 dB hearing level. The deterioration rate was 0.7%/y in the plot of maximum score against age, whereas the deterioration gradient was 0.4%/dB in the plot of maximum score against PTA1,2,4 kHz. Given the previously demonstrated rapid progression of hearing impairment, speech recognition was relatively good: at age 70, the score was still >50%.

Case selection and technique for surgical repair of aural atresia

The potential for severe distortion of the normal anatomy makes the repair of aural atresia technically difficult and risky. However, there is a good success rate and low rate of complications in selected patients. The ideal candidate for surgical repair has an isolated atresia with a well-developed atresia plate, a well-developed middle ear, ossicles, facial nerve, and mastoid, and no other severe head and neck malformations. More severe malformations may still be repairable in selected cases. Surgery is genrally delayed until approximately age 5 years to allow full development of the tympanic ring. In general, the atresia is suitable for surgical repair when the expected results can average 25 dB or less hearing level, a patent external canal, and adequate closure of the air-bone gap. The Jahrsdoerfer grading scale may be used to determine the prognosis for good hearing results. Severe microtia/anotia, hemifacial microsomia, and retrodisplacement of the mandible often correspond to low scores on the Jahrsdoerfer scale. In cases where severe malformations carry a poor prognosis for surgical repair, boneanchored hearing-assistive devices are an alternative to surgery.

Longitudinal and cross-sectional phenotype analysis in a new, large Dutch DFNA2/KCNQ4 family.

We analyzed hearing thresholds, speech recognition scores, and vestibular responses in 32 affected persons in a large family with DFNA2/KCNQ4-related hearing impairment caused by a W276S missense mutation. Linear regression analysis of individual longitudinal data revealed significant threshold progression (1 dB/y) and offset (at age zero). The mean offset thresholds were 5, 21, 40, 39, 31, and 51 dB hearing level (HL) at 0.25, 0.5, 1, 2, 4, and 8 kHz, respectively. Cross-sectional analysis of last-visit thresholds against age produced less-steep slopes and higher offset thresholds. Nonlinear regression analysis of last-visit phoneme recognition scores against age in 25 cases showed that speech recognition did not deteriorate before the third decade. A hyperactive vestibuloocular reflex was found in 3 of 11 cases: 2 persons were especially susceptible to motion sickness. Persons with this KCNQ4 mutation showed congenital, progressive high-frequency impairment without substantial loss of speech recognition during the first decades of life.

Air versus bone conduction: an equal loudness investigation

Air conduction (AC) versus bone conduction (BC) loudness balance testing was conducted at frequencies of 0.25, 0.5, 0.75, 1, 2, and 4 kHz for two groups: 23 normal hearing subjects and eight subjects with a mild to moderate pure sensorineural hearing loss. Narrow-band noise was presented interchangeably between earphones and a bone transducer fitted to the subjects. Loudness matching was carried out at each frequency and at the levels 30–80 dB hearing level (HL) (10 dB steps) in the following manner: the sound pressure from the earphones was fixed and the subject adjusted the output level of the bone transducer for equal loudness by bracketing the standard. The results revealed somewhat different loudness functions for AC and BC sound with a 6–10 dB difference in the AC and BC loudness functions for the normal hearing group over the dynamic range 30–80 dB HL at the frequencies 250–750 Hz. At the higher frequencies, 1–4 kHz, the difference was only 4–5 dB over the same dynamic range. Similar results were obtained for the sensorineural hearing-impaired group. The difference between the AC and the BC loudness functions may originate from changes with level of the AC sound path, e.g. contraction of the stapedius muscle, but also distortion from the bone transducer and tactile stimulation could have contributed to the results seen.

Management of congenital atresia ear

A total of 3 out of 5 cases of major congenital ear malformation seen in out patient department in two years in 1997 and 1998 were operated for functional reconstruction of external auditory canal, middle car and ossicular chain. 2 cases of bilateral malformation of auricle grade 2 were advised otoplastic repair prior to tympanoplasty. Out of the 3 cases operated by anterior transatretic bone approach, 2 cases had good hearing improvement in air conduction threshold of up to 30 db hearing level (averages of 0.5, 1.2 and 3 khz). One case developed external canal stenosis by six months post operatively and drop in hearing. There was no facial nerve injury in any of the cases. This paper analyses the importance of facial nerve delineation preoperatively based on its embryological development and ils relationship with temporal bone and membranous labyrinth. It also focuses on the various parameters like timing of surgery, importance of (CT) scanning, use of facial nerve monitor and surgical expertise and experience which govern the surgical intervention and its results in congenital car atresia.

Epidemiological studies on hearing impairment with reference to genetic factors in Sichuan, China.

Hearing impairment is the most common disorder of sensorineural function and is an economically and socially important cause of human morbidity. A large-scale epidemiological survey of hearing loss was conducted with 126,876 unselected subjects (63,741 male and 63,135 female) from Sichuan, China. The overall prevalence of hearing loss was 3.28% (4,164 of 126,876), and the prevalence increased with age, reaching 12.8% (1,465 of 11,421) at 60 years of age. In 73.03% of all cases (3,041 of 4,164), the hearing loss was sensorineural, and in 20.39% (849 of 4,164), it was conductive; the remaining cases (6%) were mixed hearing loss. Bilateral loss was found in 74.5% of cases (3,103 of 4,164). In 63.79% of cases (2,656 of 4,164), the degree of hearing loss was less than 55 dB hearing level (HL), and in 5.67% of cases (236 of 4,164), it was greater than 90 dB HL. The prevalence of hearing loss in childhood (<15 years of age) was 0.67% (227 of 34,157), of which 57.7% of cases were conductive and 38.8% were sensorineural. The prevalence of genetic hearing loss was 0.28% (349 of 126,876). Persons who lived in the flatlands appeared to have a higher prevalence than those who lived in the hills. Several ethnic groups, including Tibetans, the Yi, and the Lisu, had a higher prevalence of hearing loss. Presbycusis, otitis media, and genetic factors were the most commonly recognized causes of hearing impairment overall, but otitis media and genetic factors were the main causes of hearing loss in children. Causes for the observed differences in prevalence and etiologic factors between China and industrialized countries will be discussed. In China, infections and genetic factors appear to be of major importance as causes of hearing loss.

Vestibular findings in professional divers.

The purpose of the present study was to investigate possible inner ear changes related to professional diving, by the documentation of auditory and vestibular function in 13 asymptomatic professional divers and 12 nondiver controls. A higher average pure tone hearing threshold, although of no clinical significance, was found in the study group (8.53 +/- 4.85 versus 6.67 +/- 3.54 dB hearing level, p = .04). In the vestibular evaluation, the smooth harmonic acceleration test phase leads for 0.01, 0.02, and 0.04 Hz were significantly lower in the divers (0.01 Hz, 38.46 degrees +/- 7.15 degrees versus 45.83 degrees +/- 9.02 degrees, p = .02; 0.02 Hz, 21.08 degrees +/- 5.19 +/- versus 25.17 degrees +/- 5.78 degrees, p = .05: 0.04 Hz, 12.38 degrees +/- 3.69 degrees versus 14.25 degrees +/- 3.14 degrees, p = .05). We suggest that the lower smooth harmonic acceleration phase values found in the professional divers, reflecting longer vestibulo-ocular reflex primary time constants and enhancement of the velocity storage mechanism, are the result of a habituation process that augments the low-frequency response of the canal-ocular system.

Hearing loss in children with osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a genetic disorder of connective tissue. Progressive hearing loss is one of the principal symptoms of OI, affecting about 50% of adult patients. Hearing loss may also occur in childhood and results in additional disability in education and psychosocial adaptation and aggravates the physical handicap. This can be avoided by appropriate otological and audiological treatment. In a nationwide search, 254 Finnish patients with OI were identified indicating a prevalence of 4.9/100,000. Of the 60 children, 45 aged between 4 and 16 years accepting to participate the study on hearing, were evaluated by a questionnaire and clinical audiometry. Hearing loss was defined as pure tone average (PTA0.5-2 kHz) more than 20 dB hearing level (HL). A clinical geneticist determined the type of OI among the 45 patients. Two sporadic OI cases with conductive hearing loss were ascertained (4.4%): An 11-year-old girl with type IV OI with a PTA0.5-2 kHz of 35/40 dB HL and a 15-year-old boy with type IV OI with a PTA0.5-2 kHz of 27/18 dB HL. In addition, a 6-year-old girl with familial OI type I had either a congenital sensorineural deafness or early progressive deafness with PTA0.5-2 kHz of 97/103 dB HL, probably of unrelated aetiology. Hearing loss in children with osteogenesis imperfecta is less frequent than generally suspected. Nevertheless, it is recommended that audiometry is performed in children with osteogenesis imperfecta even without symptoms of hearing loss at the age of 10 years, and repeated every 3 years thereafter.

“Hyperacusis” and Origins of Lowered Sound Tolerance

“Hyperacusis” and Origins of Lowered Sound Tolerance

Auditory screening in neonates by means of transient evoked otoacoustic emissions: a report of 2,842 recordings.

The principal goal of an early identification program is to identify hearing impairment present at birth, in order to effect appropriate intervention as early as possible. Although recent research provides some evidence for the value of transient evoked otoacoustic emissions (TEOAEs) in neonate hearing screening, data are needed from large-scale clinical evaluations about the value of using TEOAEs for screening not only high-risk but also healthy neonates. A cohort of 1,421 neonates (2,842 ears) from the well-baby nursery was screened with TEOAEs in a 2-stage process. Neonates were referred from the first test prior to being discharged from the hospital. Those who failed were rescreened before the end of the first month. Those who did not pass the second-stage TEOAE screening were referred for diagnostic audiological evaluation for confirmation of hearing loss. Neonates transferred to a neonatal intensive care unit were not included in this study. Two neonates with bilateral sensorineural hearing loss of >40 dB hearing level were identified from this cohort. This study demonstrates the feasibility and the limitations of using TEOAEs as a universal hearing screening tool for all neonates. It confirms that the prevalence of hearing impairment in neonates has to be taken into account, even in a group of children without high-risk criteria. In France, a prevalence of 1.4 per 1,000 would represent 1,000 deaf children born every year, with reference to about 700,000 births per year. This study suggests that such universal screening programs would substantially increase the rate of early-identified infants with significant hearing impairment.

Clinical presentation and management of labyrinthine fistula caused by chronic otitis media.

To describe the clinical presentation and surgical management of patients with chronic otitis media complicated by labyrinthine fistula and to determine clinical indicators that predict postoperative hearing outcome, I performed a retrospective analysis at an academic tertiary care center. Thirty-four patients with labyrinthine fistula as a complication of chronic otitis media, documented at mastoidectomy, underwent postoperative audiometry. The median age was 50 years, and the duration of otologic symptoms ranged from 2 months to more than 40 years. On presentation, 3 patients had anacusis in the affected ear, while in the others, the pure tone average for bone conduction at the 0.5-, 1-, 2-, and 4-kHz frequencies was 34 dB hearing level. Nineteen patients (56%) complained of dizziness on presentation. The fistula test was positive in 14 of 28 patients (50%). The fistula was detected radiologically in 10 of 24 patients (42%). Cholesteatoma was present in 33 of 34 patients (97%). The lateral semicircular canal was the most common site of labyrinthine fistula. The cholesteatoma matrix was completely removed in 29 of 33 cases and exteriorized in the remaining 4. Of the 31 patients with measurable hearing preoperatively, anacusis occurred in 8 (26%). In 6 of these, the preoperative pure tone average for bone conduction was greater than 50 dB hearing level, and cholesteatoma matrix and granulation tissue invading the membranous labyrinth were found at surgery. I concluded that in chronic otitis media, labyrinthine fistulas occurred almost exclusively in the presence of a cholesteatoma. Postoperative hearing outcome correlated with the size of the fistula and the presence of granulation tissue invading the labyrinth. which could be predicted by the preoperative audiometry.

Age-related hearing loss, vitamin B-12, and folate in elderly women

Hearing impairment is 1 of the 4 most prevalent chronic conditions in the elderly. However, the biological basis of age-related hearing loss is unknown. The objective was to test the hypothesis that age-related hearing loss may be associated with poor vitamin B-12 and folate status. A thorough audiometric assessment was conducted in 55 healthy women aged 60-71 y. Hearing function was determined by the average of pure-tone air conduction thresholds at 0.5, 1, 2, and 4 kHz and was categorized into 2 groups for logistic regression analyses: normal hearing (<20 dB hearing level; n = 44) and impaired hearing (> or = 20 dB hearing level; n = 11). Mean age was the same (65 y) for the normal hearing and impaired hearing groups. Pure-tone averages were inversely correlated with serum vitamin B-12 (r = -0.58, P = 0.0001) and red cell folate (r = -0.37, P = 0.01). Women with impaired hearing had 38% lower serum vitamin B-12 (236 compared with 380 pmol/L, respectively, P = 0.008) and 31% lower red cell folate (425 compared with 619 nmol/L, respectively, P = 0.02) than women with normal hearing. Among participants who did not take supplements containing vitamin B-12 or folate, women with impaired hearing had 48% lower serum vitamin B-12 (156 compared with 302 pmol/L, respectively, P = 0.0007) and 43% lower red cell folate (288 compared with 502 nmol/L, respectively, P = 0.001) than women with normal hearing. Poor vitamin B-12 and folate status may be associated with age-related auditory dysfunction.

Clinical applications of transiently evoked otoacoustic emissions in the pediatric population.

Our objectives were 1) to determine whether transiently evoked otoacoustic emissions (TEOAEs) are affected by the status of the tympanic membrane (TM) and middle ear (ME) as determined by clinical examinations and tympanograms; 2) to determine the efficacy of TEOAEs in detecting hearing loss; and 3) to determine the relative effects of the ME status and hearing loss on TEOAEs. In a prospective observational study in a tertiary care children's hospital, 89 patients (169 ears; 9 ears eliminated from analyses) were examined by 2 attending pediatric otolaryngologists for otologic conditions and underwent audiologic evaluations including TEOAEs from August 1994 through May 1995. The main outcome measures were presence or absence of TEOAE whole reproducibility (WR) and reproducibility (R) at 2 kHz. Statistical analyses showed that of the 8 ME and TM conditions evaluated (normal, TM perforation, pressure equalization [PE] tube, TM retraction, tympanosclerosis, TM atrophy, ME effusion, surgery other than PE tube insertion), only the presence of ME effusion and normal examination findings had a significant effect on the results of WR and R at 2 kHz. Of the 6 different types of tympanograms evaluated (A, B, C, AD, As, B with large volume), type A, B, and C tympanograms had a significant effect on WR and types A and B had a significant effect on R at 2 kHz. Hearing losses > or = 25 dB hearing level (HL) at any of the 5 frequencies (0.25, 0.5, 1, 2, and 4 kHz) were well predicted by the absence of WR and R at 2 kHz. When clinical examination and impedance data were evaluated simultaneously with hearing status, hearing status had a greater effect on WR and R at 2 kHz. We conclude that type B and C tympanograms and the presence of ME effusion (which reflect abnormal ME status) have an adverse effect on TEOAEs. However, the presence of hearing loss is the most significant predictor of TEOAE results. The TEOAE WR and R at 2 kHz are effective in identifying patients with normal hearing and with hearing losses > or = 25 dB HL.

Comparison of distortion product otoacoustic emissions with auditory brain-stem response for clinical use in neonatal intensive care unit

Objectives: This study compares the clinical usefulness of distortion product otoacoustic emissions (DPOAEs) with the auditory brain-stem response (ABR) for neonates in the neonatal intensive care unit for the evaluation of hearing impairment. Methods: Both DPOAEs and ABR were performed on 36 neonates (67 ears) on the same day. We defined neonates as having normal hearing when the thresholds of wave V of ABR were ≤45 dB hearing level. Results: (1) We could not obtain DPOAEs at f2=977 Hz in neonates with normal hearing because of high noise floors. DPOAE recording time was 36 min shorter than that of ABR. (2) We defined as normal DPOAEs, the number of frequencies which showed the DPgram-noise floor ≥4 dB was ≥4 at 6 f2 frequencies, from 1416 Hz to 7959 Hz. (3) Normal thresholds of ABR and normal DPOAEs showed the same percentages, i.e. 68.7%, but the percentage of different results between ABR and DPOAEs was 6.0%. Conclusions: Our study indicates that DPOAEs represent a simple procedure, which can be easily performed in the NICU to obtain reliable results in high-risk neonates. Results obtained by DPOAEs were comparable to those obtained by the more complex procedure of ABR.

Long‐term hearing results following vestibular surgery in meniere's disease

The purpose of this study is to evaluate the long-term hearing changes following vestibular surgery in patients with Meniere's disease. This is a retrospective analysis of patients operated on in a tertiary referral center setting. Preoperative, postoperative, and 3- to 9-year postoperative audiograms were analyzed in two patient groups. Twenty-one patients underwent posterior fossa vestibular neurectomy (VN) and five, mastoid endolymphatic sac decompression and shunt (ELS). All frequencies, four-frequency pure-tone averages (PTAs), spondee thresholds, and speech recognition scores were compared for operated ear against nonoperated ear of VN subjects. The results were subjected to a covariance analysis. VN and ELS patients whose hearing deteriorated from "serviceable" (PTA < or =70 dB hearing level) and speech recognition > or =30%) to nonserviceable status were compared using nonparametric statistics. Progressive hearing loss beyond the rate of change of the normal contralateral ear was evident in all patients. Serviceable hearing dropped from 81% to 43% of patients an average of 4 years following VN. VN patients have significant hearing deterioration over time in the operated ear. This finding suggests that continued postoperative medical management is necessary for patients undergoing VN.